Starting / Vacuum problem?

[propagandhi]

I searched this problem and no one had a good answer so I'm restarting.

Just to start off, this is my first post here and I primarily use my 240sx as a daily driver. I used to post zilvia.net and have found much better threads here.

I replaced my leaky fuel injectors on my 1990 240sx (ka24e) with OE ones from auto store and that went presto! (it still had the almost 20 year old stock injectors, they were fine, the Orings were shot, but I replaced the injectors anyway). But now my car won't start unless I give it a little gas/throttle. And I mean only a little--my car seriously won't start unless I barely tap the gas pedal. But when it starts, it runs and idles beautifully.

Any idea why it won't start without the gas pedal?

Vacuum problem?all my vacuum lines are connected and I didn't notice any holes or tears in the lines and there are no leaks at the injectors anymore.

Could this possibly be an AIR problem?

This is probably a difficult diagnosis considering my vagueness.

Help please! Thanks.

Kevin

Modified by propagandhi at 6:42 PM 3/10/2009
Modified by propagandhi at 6:43 PM 3/10/2009

[Mercury_Hg]

I'm new, and I have the same problem, although my car requires pumping to get it started. Otherwise it runs and idles great, never stalls. Only on cold starts too, once I've been running a while I can shut if off and start it fine.

What do?

[Mercury_Hg]

Bump.

[OutToWinPAHC]

Hmm could be a number of things. You could replace the vacuum lines, but I don't think it's it. Would be a lazy crank or cam angle sensor, plugs, not enough fuel pressure right away, timing, intake / vacuum leak.



If the engine is healthy, good compression, and fuel pressure is good at the rail. Why not try a good tune up? Replace old lines, fuel filter, PCV valve, clean the throttle body and IAC, replace plugs and wires, clean harness connections, and check the ignition timing,

[Mercury_Hg]

The first guy posted over a year ago. I jacked his thread so people wouldn't yell at me to do a search. Really haven't found any straight answers.

I replaced the spark plugs and fuel filter yesterday, but now my car's idling different. It was at a solid 700-750. Now at startup it's at 1000 and goes down to 500. It might just be temperature difference (it's much colder at night which is when I noticed the difference). Startup problem remains the same. Think it might be the fuel pump? That's what I've been told, anyway.

[loyalone]

try cycling the key a few times before cranking it next time, every time you turn on the key the fuel pump runs for a few seconds, then turns off until the car starts or you cycle the key back to off then back on. if the car has no problems starting after 3 key cycles then the problem is your fuel pump. it has a built in check valve to hold fuel pressure in the lines, if the valve sticks then it will allow fuel to drain back in to the tank when the car is off, thus taking longer for the fuel to get to the motor when you turn on the key.

[Mercury_Hg]

try cycling the key a few times before cranking it next time, every time you turn on the key the fuel pump runs for a few seconds, then turns off until the car starts or you cycle the key back to off then back on. if the car has no problems starting after 3 key cycles then the problem is your fuel pump. it has a built in check valve to hold fuel pressure in the lines, if the valve sticks then it will allow fuel to drain back in to the tank when the car is off, thus taking longer for the fuel to get to the motor when you turn on the key.

Thanks!

I've actually tried this, but I only turned it on once for a long time, hoping it'd work (I didn't know it doesn't run continuously).
I can't try now because I just drove a couple hours ago, but I'll try this in the morning.

If it's the valve, where is the valve at?

[loyalone]

it's built in to the pump, i just thought of something else that would have the same effect, thats the fuel pressure regulator. you need a gauge to check it.

[Mercury_Hg]

it's built in to the pump, i just thought of something else that would have the same effect, thats the fuel pressure regulator. you need a gauge to check it.

EDIT: I tried starting the car the way you said, and it wouldn't until I pumped the accelerator some. It was quiet enough that I could hear the pump activate and then cut off each time I turned the key.

So it's probably not my fuel pump?

I'm reasoning it's the fuel pressure regulator because if it was a valve on the pump, wouldn't pressing the accelerator have no effect and I'd just have to wait for it pump all the way to the front?
If it's the regulator, opening the throttle would cause it to increase the pressure and maybe it's getting the pressure up enough to start.

Hmmm .

[loyalone]

If it's the regulator, opening the throttle would cause it to increase the pressure and maybe it's getting the pressure up enough to start.
.

good thought. i'd try replacing it.

[OutToWinPAHC]

it's built in to the pump, i just thought of something else that would have the same effect, thats the fuel pressure regulator. you need a gauge to check it.

EDIT: I tried starting the car the way you said, and it wouldn't until I pumped the accelerator some. It was quiet enough that I could hear the pump activate and then cut off each time I turned the key.

So it's probably not my fuel pump?

I'm reasoning it's the fuel pressure regulator because if it was a valve on the pump, wouldn't pressing the accelerator have no effect and I'd just have to wait for it pump all the way to the front?
If it's the regulator, opening the throttle would cause it to increase the pressure and maybe it's getting the pressure up enough to start.

Hmmm .

Pressure a the rail should stay balanced, the injectors gate on more frequently with an increased duration.

[loyalone]

Pressure a the rail should stay balanced, the injectors gate on more frequently with an increased duration.

so you think dirty or bad injectors?

[Mercury_Hg]

Pressure a the rail should stay balanced, the injectors gate on more frequently with an increased duration.

so you think dirty or bad injectors?

I'm honestly not sure what the guy before you said.

One of my injectors has been replaced, looking at them. One's bright red and the rest are weathered. I'm on a budget though and I don't want to replace anything I don't have to right now. Is there anything I can do before I replace the injectors? Try cleaning maybe? What else?

[loyalone]

i don't think its an injector, regulator, or fuel pump anymore. when you pump the accelerator pedal when cranking the ecm gives the car more fuel, if you hold the pedal to the floor it will not give the car any fuel at all. i don't know if that helps you or not.
Also it's not likely, but maybe the IAC is sticking closed and not letting any air in the motor, one way to test that would be pulling any vacuum line off the intake before you start it. then see if it starts right up. i really don't think thats the problem though as you would probably have idle problems.

[Mercury_Hg]

I'll try cleaning the IAC and let you know if it helps. I would remove a hose but I'm not sure which hose is the right one :P. I'm pretty damn new to this stuff.